Definition
A historical term for the high-altitude airspace in which all aircraft were required to operate under instrument flight rules (IFR), be equipped with a transponder, and follow ATC clearances at all times. In the United States, this airspace extended from 18,000 feet MSL up to and including flight level 600. It has since been redesignated as Class A airspace under the current alphabetic airspace classification system.
Plain English
Old name for the high-altitude airspace where every aircraft must be on an IFR flight plan and under air traffic control. Today it is simply called Class A airspace.
Context Anchor
Seen in FAA acronym lists and in discussions of controlled airspace, especially older or historical wording for high-altitude airspace control.
Derivation
‘Positive control’ means active, mandatory control by ATC — every aircraft is known to controllers and following their instructions, as opposed to airspace where pilots may operate VFR without ATC involvement.
Why Pilots Care
Pilots must comply with all ATC clearances and instructions; no visual separation or pilot discretion is permitted.
Intuition Check
Do not read positive as meaning good or safe by itself. Here it means active, direct control by air traffic control.
Example Sentence 1
The instructor mentioned that what the older manual calls positive control airspace is now known as Class A airspace.
Example Sentence 2
In positive control airspace the controller issues vectors to ensure all aircraft remain separated by the required distances.